Origin and evolution of the Volga mountain oak forests

Based on our analysis of the spore-pollen complexes of the Holocene, the controversial issue of the primary origin of the Volga mountain oak forests of the Volga Upland has been resolved. The main stages of their formation have been restored, namely: “tundra-steppe” with wormwood-haze, horsetail and fern cenoses (forest zone 10, 10,300–9,300 years ago); cereal-forb, wormwood and wormwood-haze steppes, steppe sparse birch forests (zone 9, 9,300–8,500 years ago); gramineous-forb and sod-gramineous steppes and very sparse birch woodland (zone 8, 8,500−8,000 years ago); birch forests and grass-forb steppes, the emergence of the Volga upland oak forests (zone 7, 8,000–6,000 years ago); the formation and flowering of oak forests (zones 6– 4, 6,000–2,500 years ago); stepping and thinning of deciduous forests and sod-grass steppes with a noticeable participation of weed and cultivated species, the emergence of the first agrocenoses (zone 3, 2,500–700 years ago); and the emergence of secondary undergrowth birch forests, oak forests, lime forests and aspen forests. Secondary meadow and sandy steppes with an abundance of weed species (ruderal, pasqual and segetal). The emergence of secondary steppes in the place of deforestation. Expansion of agrocenoses (zone 2, 700–300 years ago); reduction in the area of Volga upland oak forests, massive introduction of maple and, singly, pine (zone 1, 300 years ago – to the present). It has been concluded that the Volga upland oak forests are the native vegetation formation of the Volga Upland, formed about 6,000 years ago, long before the beginning of human economic activity. The modern appearance of this territory was formed about 400–300 years ago, with the beginning of the mass development of the territory.